There are a large number of people with impaired hearing. According to National Health Promotion and Disease Prevention Objectives, impaired hearing becomes increasingly common after age 50, affecting 23% of people aged 65 thru 74; 33% of those in ages 75 thru 84, and 48% of those who are 85 and older. Hearing impaired people generally have trouble understanding conversations conducted over a telephone phone in a noisy environment. The most common hearing losses are associated with higher pitch sounds, although lower pitch tones may also be affected. This can have an adverse impact on audio communications, such as telephone conversations. For example, higher pitch sounds are important for understanding speech (e.g. many important consonants are comprised mainly of the higher pitch sounds).